Field of the Invention
The invention pertains to the field of crude oil compositions. More particularly, the invention pertains to compositions and methods for raising the flash point of crude oil compositions.
Description of Related Art
The U.S. federal government has assigned to the Environmental Protection Agency (EPA) the responsibility of regulating man-made volatile emissions, which may pollute the air and atmosphere. The EPA has listed a group of Volatile Organic Compounds (VOCs) as “Exempt VOCs”, which is published in the Federal Register under 40 CFR 51.100(s), which is hereby incorporated by reference herein, and addendums. All other VOCs are restricted for use and weight-limited for emission discharge into the atmosphere and environment. Formulators and compounders of products using VOCs are challenged to use and obtain the required VOC combinations for use in their products, to comply with toxic emissions, and to provide for safety in manufacturing, shipping, storage, and ultimate use. VOCs are further sub-classified based upon their vapor pressures, boiling points, and flash points. The flash point of the VOC becomes a critical factor for emission discharge and safety, because it is the point at which the liquid becomes a volatile vapor, mixes with oxygen, and thereby acquires its most combustible or flammable state. Flash point, as used herein, refers to the lowest temperature at which a volatile liquid can vaporize to form an ignitable mixture in air. In the United States, the Environmental Protection Agency (EPA) and the Department of Transportation (DOT) have classified such compounds based on their volatilities or “flash points”.
The current EPA and DOT Volatile Organic Compound (“VOC”) classifications are as follows:
Class I liquids (flammable) flash point at or below 100° F.
Class II liquids (combustible) flash point from 100° F. to below 140° F.
Class III liquids (combustible) flash point above 140° F. to below 200° F.
International standards are generally stricter, with 43° C. (109.4° F.) generally being the separation point between flammable and combustible liquids.
There are currently six commonly used exempt VOCs on the U.S. federal list of acceptable VOCs. Of the six, four have flash points below 10° C./50° F. and they are therefore classified as “flammable and hazardous”, thus rendering their respective use to safe and unpopulated areas. P-Chlorobenzotrifluoride (PCBTF) has a “combustible” flash point rating of 43° C./109° F., and propylene carbonate lists as “combustible” with a flash point of 107.8° C./226° F.
Organic solvents, such as acetone, xylene, ketones, esters, ethers, aliphatic hydrocarbons, and aromatic hydrocarbons such as benzene, are widely used as additives for industrial and commercial purposes. Due to the high volatility of these compounds, their uses are regulated by many countries' governmental agencies. Generally, the more flammable a solvent, the more restrictions exist on its use. Further, manufacturers that utilize solvents must handle the more flammable liquids more carefully and must address issues involving atmospheric volatility and worker health concerns due to excessive exposure to these chemicals.
“Green” solvents are regarded as such because of their sources of origin (non-petroleum based) and the fact that they biodegrade readily after use without environmental damage. Green solvents include, but are not limited to, certain alcohols such as methanol, ethanol, benzyl alcohol, certain acetates, certain esters, and turpentine. The problem with these solvents, however, is that due to their high volatility, they are considered hazardous air pollutants which violate Federal and State emissions regulations. Ethyl lactate, one example of a green solvent, has a flash point of about 115° F., which despite not being considered a Class I VOC, is still combustible, which limits its potential uses. Green esters, such as N-butyl propionate, ethyl lactate, and methyl soyate, are also considered combustible, with flash points ranging from 115° F. up to 250° F. However, they are slow to evaporate and exhibit good solvating characteristics when used in blended compositions. Nevertheless, this group of solvents is considered environmentally clean and could be utilized more extensively if their volatilities could be reduced.
Terpenes are a large and varied class of hydrocarbons with the molecular formula (C5H8)n and are produced naturally by a wide variety of plants and trees, such as conifers and pines. Terpenes are derived biosynthetically from units of isoprene, which has the molecular formula C5H8. The term “terpene” is sometimes used broadly to also include the terpenoids which are terpenes that have been chemically changed or modified, such as through oxidation. A terpene or terpene component, as used herein, however, may be any hydrocarbon, natural or synthetic, formed from isoprene units. Terpenes as well as terpenoids, are the primary ingredients of the essential oils of many types of trees, plants, and flowers, including citrus fruits. Terpenes are the major components of rosin (resin) as well as turpentine produced from gum rosin (resin).
The terpenes are generally classified sequentially by the number of isoprene units they contain as hemiterpenes (one isoprene unit), monoterpenes (two isoprene units), sesquiterpenes (three isoprene units), diterpenes (four isoprene units), sesterterpenes (five isoprene units), triterpenes (six isoprene units), and tetraterpenes (eight isoprene units).
As with other plant essential oils, terpenes are major constituents of the essential oils of citrus fruits. However, they are removed before the essential oil is used for flavoring beverages and foods because they tend to produce undesirable tastes when permitted to oxidize and polymerize.
Terpene hydrocarbons are liquid distillates separated from rosin pitch or sap from conifers, pine trees, citrus, and varied vegetation. The volatile terpene hydrocarbons, Chemical Abstracts Service Number (CAS#) 8006-64-2, are non-oxygenated with the molecular formula C10H16. Common names include terpenes, diterpenes, pure gum turpentine (PGT), oil of turpentine (OT), and limonene. Commercial areas of use include in paint thinners, paint strippers, cleaners, disinfectants, and pharmaceuticals.
The term “terpene” is derived from the word “turpentine”. Turpentine is a volatile fluid which is distilled and refined for further commercial uses. The most common terpenes obtained from rosin (resin) distillation are the bicyclic terpenes alpha-pinene (α-pinene), beta-pinene (β-pinene), delta-3 carene (δ-3 carene), and sabinene, the monocyclic terpenes limonene and terpinolene, and smaller amounts of tricyclic sesquiterpenes longifolene, caryophyllene, and delta-cadinene. Rubber, which is a polyterpene, is one of the most widely known terpenes.
Turpentine, which is also known as spirit turpentine, oil of turpentine, and wood turpentine, is obtained by the distillation of resin from trees, usually pine trees. Turpentine prepared in this manner includes mostly alpha-pinene and beta-pinene, two terpene isomers. The exact composition of turpentine may vary from batch to batch depending on the distillation conditions and the resin source. As a solvent, turpentine has been used in varnishes and for thinning oil-based paints.
Pure gum turpentine is a complex formulation made of α-pinene (CAS#80-56-8) 40%-55% weight, β-pinene (CAS#127-91-3) 25%-35% weight, and the balance mixed trace terpenes. Pure gum turpentine is 99.5%-100% volatile, evaporating slightly less (0.9) than the reference standard (butyl acetate (1.0)), has a flash point of 35° C./95° F., a boiling point of 155-180° C., and a Kauri-butanol (Kb) value greater than 50, and is generally soluble in organic solvents.
U.S Pat. No. 8,414,797, issued Apr. 9, 2013 to Howard et al. and hereby incorporated by reference herein, discloses compositions and solvent mixtures including at least one organic solvent and at least one terpene. The solvent formulation raises the flash point of the mixture.
When a terpene is modified chemically, such as by oxidation or rearrangement of the carbon skeleton, the resulting compound is generally referred to as a terpenoid. Terpenes and terpenoids are typically derived from plants, trees, flowers, and other vegetation. They come in the form of liquids, solids, waxes, oils, and alcohols. Terpenes and terpenoids may be formed as acyclic, monocyclic, or polycyclic structures. Sometimes alternatively referred to as “isoprenoids”, terpenoids are derived from five-carbon isoprene units and can be classified as “modified terpenes”, where methyl groups have been moved or removed, or oxygen atoms added. Some researchers use the term terpene to include all terpenoids.
Terpenes and terpenoids in various forms have been used for centuries in fragrances due to their compatibility with other compounds and their minimal negative environmental impact. Terpineol, a terpene alcohol, has the chemical formula: C10H18O and is found in three isomeric forms, alpha, beta, and gamma, with beta-terpineol being non-naturally occurring. Terpenes and terpenoids have been used for other purposes, such as disinfectants, cleaning compounds, soaps, cosmetics, and colognes. They are also known to add, enhance, or mask the odor of products which might be offensive to humans or animals
Terpene alcohols generally have the structure of terpenes except that they include at least one hydroxyl group. A terpene alcohol or terpene alcohol component, as used herein, may be any compound, natural or synthetic, formed from isoprene units and having at least one hydroxyl group. Terpene alcohols are also derived from plants, trees, flowers, and other vegetation which allows their classification as “green compounds”. Terpene alcohols are also divided into groups determined by the number of carbon atoms and repeating isoprene units. Terpene alcohols may be formed as acyclic, monocyclic, or polycyclic structures. Terpineol, a terpene alcohol, has the chemical formula: C10H18O and is found in three isomeric forms, alpha (α), beta (β), and gamma (γ), with β-terpineol being non-naturally occurring. Terpene alcohols have been used for many purposes, including, but not limited to, disinfectants, cleaning compounds, soaps, cosmetics, and colognes. They are also known to add to, enhance, or mask the odor of products which might be otherwise offensive to humans or animals.
U.S. Pat. No. 7,273,839, issued Sep. 25, 2007 to Koetzle and hereby incorporated by reference herein, discloses the use of terpene alcohols with organic solvents and blends of solvents to increase the flash points of these solvents. Koetzle also discloses a method to decrease the flammability of normally flammable solvents using terpene alcohols, by blending the terpene alcohol into the flammable solvent. Koetzle discloses increasing the flash points of acetone, methanol, ethyl acetate, ethanol, and xylene by 50 to 60° C., by addition of 12-14% terpineol. Koetzle also discloses solvents blended with other organic solvents to produce performance solvents, such as paint strippers with flash points greater than 140° F.
Recent technological advancements in oil drilling have led to the extraction of crude oil from underground sites previously inaccessible to or unprofitably accessible by conventional oil drilling methods. Many of these new extraction sites, such as the Bakken Shale region covering parts of North Dakota, Montana, and Saskatchewan, Canada, do not have the appropriate refineries nearby to process the crude oil or pipelines to transport the crude oil to an appropriate existing refinery. This has led to an increase in the transport of crude oil by rail and on roads and highways.
It was recently reported that in 2014, more than half a million railroad tank cars of crude oil was transported, compared to just 9,500 railroad tank cars of crude oil in 2008. A number of recent railroad accidents involving tank cars transporting crude oil have led U.S. and Canadian transport officials to enact new safety rules for tank cars transporting crude oil.
Crude oil or a crude oil composition, as used herein, is an unrefined, naturally-occurring, substantially liquid mixture of hydrocarbons and other liquid organic compounds and any impurities located in and extracted from geological formations underground and formed from large quantities of dead organisms as a result of decay, heat, and pressure over millions of years. The exact composition of a crude oil varies from location to location depending on the materials from which and conditions under which it was formed. Crude oils are highly flammable with a flash point below 100° F. Although the flash point varies from one crude oil sample to another, crude oil flash points are generally in the range of 20 to 90° F.
Crude oils have been classified generally based on where they are extracted, their density, and their sulfur content. Light crude oils have a relatively low density, and heavy crude oils have a high density. Sweet crude oils have relatively little sulfur, whereas sour crude oils have a relatively high sulfur content. Light, sweet crude oils are generally the most desirable.
Petroleum or a petroleum composition, as used herein, is any form of refined or unrefined crude oil. Crude oil is conventionally refined by distillation into petroleum fuel fractions including liquefied petroleum gas, butane, gasoline, jet fuel, kerosene, fuel oil, and diesel fuel.